From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tiwei Bie Subject: Re: [PATCH] vhost: prevent disabled rings to be processed with zero-copy Date: Wed, 27 Feb 2019 18:10:32 +0800 Message-ID: <20190227101032.GA32256@dpdk-tbie.sh.intel.com> References: <20190227085428.13666-1-maxime.coquelin@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Cc: dev@dpdk.org, stable@dpdk.org To: Maxime Coquelin Return-path: Content-Disposition: inline In-Reply-To: <20190227085428.13666-1-maxime.coquelin@redhat.com> List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" On Wed, Feb 27, 2019 at 09:54:28AM +0100, Maxime Coquelin wrote: > The vhost-user spec says that once the vring is disabled, the > client has to stop processing it. But it can happen when > dequeue zero-copy is enabled if outstanding descriptors buffers > are still being processed by an extranl NIC or another guest. s/extranl/external/ > > The fix consists in draining the zmbufs list to ensure no more > descriptors buffers are in the wild. > > Note that this fix is only working in the case REPLY_ACK > protocol feature is enabled, which is not the case by default > for now (it is only enabled when IOMMU feature is enabled in > the vhost library). > > Fixes: b0a985d1f340 ("vhost: add dequeue zero copy") > Cc: stable@dpdk.org > > Signed-off-by: Maxime Coquelin > --- > lib/librte_vhost/vhost_user.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c > index 36c0c676d..ef947b90c 100644 > --- a/lib/librte_vhost/vhost_user.c > +++ b/lib/librte_vhost/vhost_user.c > @@ -1336,6 +1336,10 @@ vhost_user_set_vring_enable(struct virtio_net **pdev, > "set queue enable: %d to qp idx: %d\n", > enable, index); > > + /* On disable, rings have to be stopped being processed. */ > + if (!enable && dev->dequeue_zero_copy) > + drain_zmbuf_list(dev->virtqueue[index]); It might be better to drain the zmbufs list after calling application's vring_state_changed() callback, so there will be a chance for applications to take some actions first if they want. Overall this looks good to me, Reviewed-by: Tiwei Bie Thanks! Tiwei